Tall is good! Again, what is "in the 70s"? Is that 78, 79 or is it 71, 72?
See how different that is? My thinking is the bottom of the enclosure should be room temperature.
If you have that, then yeah, you're okay for a while.
Just for information, a really good measurement to try to get (in some low stress way) is nose to vent because that's a better measure of the size of your chameleon. Tails can be a bit varied. You don't need to drag him out and put him on a ruler, but at some point when you have him out it would be good to photograph him with something measurable in the picture (not your hand unless you include a picture of your hand with a ruler!!!). I'm thinking things like soda cans, beer bottles...stuff like that which people can use as a reference (best: a ruler!).